The proposed research in experimental animals is designed to 1) determine the relationship of splenic mass to immune function of the spleen, and 2) develop and evaluate therapeutic alternatives to splenectomy which reduce excessive or normal splenic function. Humoral immunity and bacterial clearances will be examined in rats after removal, reduction and augmentation of splenic mass in comparison to normal animals. This project should shed light on the relationship between blood flow and immune function in the spleen as well as on the changes in splenic function which occur in a variety of disease states.